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. 2001 Feb 13;98(4):1751–1756. doi: 10.1073/pnas.98.4.1751

Figure 1.

Figure 1

Identification and structures of CD40 isoform mRNAs. (A) CD40 mRNA comprises sequences included in exons 1–9 of this gene. The relative position of PCR primers used for RT-PCR and population assay are indicated by arrows (P1 to P7). Positions of the first ATG and the stop codon for translation of CD40 are indicated. (B) CD40 mRNA was analyzed by RT-PCR using P1 and P2 primers (as in A), and cytoplasmic RNAs from LPS-activated (18 to 24 h) cells. Three different-sized PCR products (III, I+IV, II+V) were detected by Southern blot hybridization using CD40 cDNA as a probe. (C) Structure of CD40 isoform (type I–V) mRNAs generated by alternative splicing. Positions of alternative splicing are indicated by thick solid lines. The alternative splice site in exon 8 (5 bp downstream of the 5′ end of the exon 8) is indicated by dotted lines. Position of stop codons for translation are indicated by arrow heads. (D) Population assay of CD40 isoform mRNAs. All PCR products amplified by using P3 and P4 primers (as in A) and cytoplasmic RNA from LPS-activated A20 cells were cloned without size fractionation. The number of each isoform is indicated with the percentage in brackets.